Blog Post

Viva Questions:

1. What is Light Emitting Diode (LED)?
2. How it is different from Si/Ge diode?
3. How LED works?
4. In the photoelectric effect, a suitable frequency of photon falls on an electron in an atom and ejects the electron. In LED when electron-hole recombination takes place a photon emits. How do you see these two phenomena?

5. Why do you put equal two different energies like eV and hv, what is the condition for that?

6. Which material do we use an LED?

7. How photons emitted from the LED and from which section of the LED?

8. How do you explain the working of LED by using the energy band diagram in forward biasing?

9. What happens when you provide the forward bias to the LED in terms of conduction band & valence band in the depletion region?

10. Why do not LED starts to glow immediately when you provide the forwarding bias to that?